My son graduates from high school in the Spring and will go away to college in the Fall. We will need to replace his 7 year old MBA, which has been terrific. So, I went to our local Apple store yesterday to get some information about the reliability of the new MBA keyboard. It's a large store in a popular mall, so they get a fair amount of volume and deal with a lot of repair issues.
I spoke with an employee that seemed reasonably knowledgable, and she listened very carefully to my questions and concerns. She asked if I could wait around for a few minutes so she could talk to some of the techs in the backroom about possible keyboard issues on the 2018 MBA. When she returned, she told me that there where two techs available and they both told her they had never seen a keyboard failure with the 2018 MBA. They had dealt with issues on the older MacBooks and MacBook Pros.
Of course, this is all very anecdotal......but, this entire thread and most of the posts on MacRumors are anecdotal. Also, I found the employee to be very credible, and I think she really did make an effort to talk to some techs about my concern. In other words, I don't think she went to the back room, sat around for 5 minutes, didn't talk to anyone, and then came back and just lied to my face.
I just thought I would add another reference point.